ABSTRACT This Phase I STTR application from Caeli Vascular, LLC entails a 12-month period focused on the development of a novel endovascular venous thrombectomy device. The PI is a vascular surgeon with biomedical research and entrepreneurship experience, and is supported by a team of highly qualified investigators, including a vascular biologist, neurosurgeon, veterinarian, biomedical engineer, mechanical engineer, and a marketing and management expert. The primary objective of this application is to test a catheter-based venous thrombectomy device designed to address all current gaps in the state of the art for the treatment of large volume deep venous thrombus (DVT) in the inferior vena cava (IVC) and iliac veins (iliocaval venous segment). Each year, more than 900,000 Americans will develop a large-volume DVT. As many as 100,000 will die as a result of a complication within 2 weeks of diagnosis. Approximately 50% of patients with large-volume acute DVT will develop a severe complication such as fatal pulmonary emboli (PE). Treatment options of large volume DVT in the iliocaval venous segment are limited, and currently available percutaneous endovascular thrombectomy devices have various shortcomings that affect treatment efficacy and safety. Major gaps include increased risk of intra-procedural thrombus embolization leading to PE, poor thrombolytic penetration leading to increased bleeding risk, and inability to completely remove thrombus leading to unresolved DVT. To address all the gaps in the state of the art of percutaneous venous thrombectomy devices we designed and prototyped the Hydra Catheter. Unique and proprietary features of the Hydra Catheter include adjustable ecapsulation balloons, an infusion catheter segment to facilitate delivery of thrombolytics and isovolumetric infusion/suction, and a built-in leaflet agitator. Our preliminary findings demonstrated high efficacy compared to current FDA- approved mechanical suction thrombectomy catheters. Our multi-disciplinary team of investigators proposes to test feasibility of the Hydra Catheter prototype in an ex vivo vena cava flow model in the following clinically- relevant specific aims: Aim I: Confirm that Hydra catheter adjustable balloon encapsulation design eliminates embolization of distal thrombus fragments. Aim II: Demonstrate that isovolumetric suction can clear a venous ?treatment zone? without risk of venous wall collapse and distension damage. Aim III: Determine whether Hydra Catheter leaflet agitator increases blood clot fragmentation and grasping. By completing these proposed aims we will establish the mechanical feasibility of the novel Hydra catheter prototype for the treatment of large-volume iliocaval DVT. These findings will allow us to prepare Phase II pre- commercialization studies necessary for FDA-regulatory clearance through an anticipated 510(k) mechanism based on predicate devices designed for either mechanical or chemical thrombectomy.